The present invention concerns a rotary crane, especially an offshore crane of the king post type, with a pylon which can be anchored to a base plate, platform, etc., a turntable mounted to revolve on the longitudinal axis of the pylon, a crane boom borne by the turntable, and rotating gear for rotating the turntable on the pylon, where the upper support of the turntable includes a mount seated on an upper section of the pylon, in such a manner that it can be rotated, which upper mount has an axial support surface to brace axially against the pylon, as well as a radial support surface to brace radially against the pylon, and suspension means to suspend the turntable.
A rotary crane of the king post type is known from U.S. Pat. No. 5,328,040. The support pylon or king post of this crane has at its upper end a support pin which protrudes from the front of the pylon. A mount 34 is positioned on and can rotate around this support pin, on which the turntable of the crane is supported. For this purpose the mount has two upright, approximately circular, support discs 38 which face each other. The turntable is positioned on these circular-arc support discs with appropriate matching counter-components, so that the axial forces acting on the mount or the upper support are centered. In addition to said mount, the turntable is supported radially on the upper support via a pin positioned radially to the support pin and a corresponding radial support, to support the horizontal components of the support force.
This known support method can be improved from several points of view. Particularly disadvantageous is the fact that it is a support design that is expensive, as a whole. It is relatively difficult to maintain, as the multi-part construction has to be disassembled. To gain access to the upper support, the entire turntable has to be raised. This requires hydraulic jacks, for which in turn appropriate contact points in the form of flanges and the like must be welded on.
Another problem is the strength and security of this support. Ultimately the entire burden created by the turntable, pylon, and lift load depends on four screws which hold the pertinent parts of the upper support together. This is urgently in need of improvement from the aspect of safe force application.
The task of the present invention is therefore to create an improved rotary crane of said type which avoids the disadvantages of the state of the art and further develops it in an advantageous fashion. Especially, an improved upper support is to be created for the turntable on the rotary pylon which, on the one hand, is simple in construction and simple to maintain and, on the other hand, permits a safe transfer of forces from the turntable to the pylon.
According to the invention, this problem is solved by a rotary crane, especially an offshore crane, of the king post type, with a pylon which can be anchored on a floor plate, platform, and similar equipment, a turntable housed to revolve on the longitudinal axis of the pylon by means of an upper support and a lower support, a crane boom supported by the turntable, and rotating gear for rotating the turntable on the pylon, in which the upper support of the rotary stage has a mount which is positioned on an upper end section of the pylon and which can rotate, which mount has an axial support surface for axial support on the pylon as well as a radial support surface for radial support on the pylon and suspension equipment for suspending the turntable, in which an inclined plane is provided on the pylon and a lifting component can be attached to the mount, which lifting component runs along side the inclined plane when the support is rotated on the longitudinal axis of the pylon, lifting the mount with its axial support surface from the pylon. Preferred embodiments of are described herein.
The rotary crane thus has a wedge-shaped surface on the pylon, and, on the mount, an attachment device for attaching a hoisting device which, when the mount rotates on the longitudinal axis of the pylon, runs along the pylon inclined plane and lifts the mount with its axial support surface from the pylon. This facilitates access to the support in a particularly simple manner. After the attachment of the lifting component to the mount, all that is needed is to activate the rotating gear so that the turntable and the mount, which is fixed immovably to the pylon revolve on the pylon with respect to the longitudinal axis of the pylon. The lifting component thereby makes contact with the screw-pitch inclined plane on the pylon, and lifts the mount and with it the entire turntable around a piece on the pylon, in such manner that the axial support surfaces come free and are accessible for maintenance. The lower support, as well as the rotating gear drive, are designed in such manner that they can slide axially for this purpose.
Conversely, another aspect of the present invention can provide for the hoisting device of the rotary crane to be mounted on the pylon with an inclined surface on the mount, such that when the mount rotates around the longitudinal axis of the pylon, the lifting gear attached to the pylon lifts the mount with its axial support surfaces from the pylon. Here too, simply by actuating the rotating gear the turntable as a whole and especially the upper mount can be lifted relative to the pylon. Preferably, however, provision is made for the above-described arrangement of the inclined surface on the pylon and the possibility of anchoring the lifting component on the mount, since advantages in terms of simplicity of design can thereby be achieved.
The rotary crane thus has a hoisting device for lifting the turntable or the upper mount relative to the pylon, with the hoisting device being driven by the rotating gear of the rotary crane. All that is needed is a lifting component which works together with the inclined plane, particularly in the form of a lifting pin anchored on an attachment device provided for that purpose. Actuation of the rotating gear produces the desired lifting or lowering of the mount of the facing support surface of the pylon.
In a further development of the invention, the pylon has at its upper end a flange-shaped annular surface extending radially on whose surface segmented bearings are positioned, on which the mount with its axial annular surface is supported, the bearings being fixed rigidly on the annular surface and being designed to be separable from it. This permits easy changing of the thrust bearing, which is subject to wear. After lifting the mount, all that is needed is to remove the worn axial bearing segments and replace them with new ones.
Preferably the bearings can rest in matching recesses on the flange-shaped annular surface of the pylon. Especially, retaining pieces in the form of cylindrical heads can be provided which, on the one hand fit precisely into recesses in the annular surface and on the other hand fit positively into lined-up recesses in the bearing blocks. The bearings and the annular surfaces thus have notches in the form of recesses for the retainer pieces, which, when the bearings fit precisely align together on the annular surfaces. This causes the bearing surfaces to be on the one hand attached adequately to the annular surfaces of the pylon and on the other hand to be easily replaced for maintenance purposes. The bearings thus do not have to be attached with, for example, screws.
In a further development of the invention, a support pin extends beyond the flange-shaped annular surface on the front of the pylon at its upper end. Said support pin is surrounded in ring fashion by the mount, and the mount with its radial support surface rests on said support pin. In a further development of the invention, the free end of the front annular surface of the support pin could be the seat of the inclined plane which allows the mount to be lifted axially. The inclined plane could fundamentally be located in another position. However, it is particularly advantageous if the contour of the support-pin front ascends toward the circumference, since the lifting component, especially a support pin, can then be positioned simply so that it will grip the inclined plane.
Especially, the mount can have a bearing guide immediately adjacent to the inclined plane, which can extend radially, so that the lifting component, especially a lifting pin transverse to the longitudinal axis of the pylon, can slide over the inclined plane. The lifting component can be slid forward and backward in the bearing guide. When pushed forward on the inclined plane, the lifting component projects beyond the bearing guide and extends over the inclined plane.
To distribute the active forces, preferably two attachment devices are positioned symmetrically on the mount so that two lifting components can be installed and can then run along two appropriate inclined planes. Especially, the mount can have as bearing guide two guide lugs with guide holes extending radially and positioned on an upper surface of the mount, that is, on the upper support-piece side when the mount is installed on the vertical pylon. Two lift pins can be inserted through the guide lugs, which preferably are diametrically opposite each other on the mount, so that the lift pins rest on two inclined planes provided on the pylon front, especially on its support pins.
To prevent the mount from tipping over as a result of wear of the radial support or as a result of manufacturing imprecision, in a further development of the invention the support-piece suspension equipment has a tip axis which extends transversely to the longitudinal axis of the pylon and allows the turntable to tip or swing on said tipping axis relative to the mount. The tipping axis is preferably perpendicular to a longitudinal center plane of the crane, which extends from the crane boom and the pylon. Tipping movements of the rotary crane occur, particularly in the longitudinal center plane because of the loads suspended on the crane boom, particularly in said longitudinal center plane, so that the tipping link between the mount and the turntable effectively ensures that a center-radial load is introduced on the thrust support and effectively prevents increased internal stresses because of distortion in the turntable. A certain amount of tipping is permitted and desired in order to counter increased internal stresses.
Preferably, the mount can have two support discs parallel to each other on opposite sides and positioned upright, having a circular-arc external contour and rigidly connected with the mount as a whole. The turntable rests on the circular-arc external contour of the support discs with complementary circular-arc recesses.
To prevent distortions in the upper support, the turntable is supported on the upper support exclusively by the mount on the pylon, and is in turn supported on said mount exclusively by the two support discs of the mount. Thus, there is especially no additional radial support between the turntable and the pylon on the upper support, for example below or above the mount. Also, the radial forces are borne exclusively through the hood-shaped mount.
Preferably the turntable does not have in the area of the upper support any cross-structure for the attachment of the mount. The turntable, which essentially can consist of two longitudinal arms extending along the sides of the pylon, is preferably suspended directly with the longitudinal arms on the circular-arc support discs of the mount. The side arms can have appropriate recesses for this purpose, preferably in the form of bowl-shaped shoulders projecting into the center, with which shoulders the turntable rests on the support discs of the mount. A cross-plate between the longitudinal arms for the purpose of attaching the mount can be dispensed with.
In a further development of the invention, the mount is designed in one piece. Between the pylon and the mount there are merely bearing blocks, made of a good friction-bearing material, and specifically bearing blocks which act radially and bearing blocks which act axially.
The mount can have a sleeve-shaped collar which surrounds a perimeter surface of the support pin at the end of the pylon, as well as a flange built in a single piece with the collar and protruding radially outward from the collar. An internal perimeter surface of the collar forms the radial support surface, on which the bearings can be positioned, and the support-piece flange forms the thrust bearing surface which rests on the corresponding bearings attached to the pylon. Attachment eyes can be provided as attachment devices for the lifting component, said attachment eyes being positioned on the collar at the end which faces the flange.